Radio Base Station with Asymmetric Interface Between Baseband Unit and RF Unit

ABSTRACT

The invention relates to an integrated antenna node ( 22 ) for use in wireless communication in a communication system ( 20 ), the wireless communication involving uplink and downlink physical-layer processing. The integrated antenna node ( 22 ) is adapted to perform, for at least one set of corresponding uplink and downlink physical-layer processing functions, only the uplink physical-layer processing functions or the corresponding downlink physical-layer processing functions. The invention further relates to a main node ( 21 ), a radio base station ( 28 ), computer programs and computer program products.

TECHNICAL FIELD

The technology disclosed herein relates generally to the field ofwireless communication systems, and in particular to radio base stationarchitectures of such wireless communication systems.

BACKGROUND

In the early days of wireless telecommunication, the radio base stationarchitecture comprised two distinct parts: an active part comprisingdigital and analog components required for signal processing and apassive part comprising filters and antennas for transmitting/receivingradio-frequency (RF) signals. The link between these two parts was ahigh-power analog radio-frequency (RF) link. This RF feeder link oftenrequired long cables of high quality and large dimensions, whichentailed high costs for keeping unavoidable signal-quality losses andpower losses to a minimum.

Power amplifiers and other RF blocks have recently been integrated moreclosely with the physical antenna in order to avoid the above-describedlink and the architecture of the radio base station is changing. FIG. 1illustrates, at the left-hand side, the traditional architecture with abase station module 1 interconnected with an antenna node 2 by means ofthe analog RF feeder link 3. At the right-hand side of FIG. 1, theevolution towards integrating RF functions more closely with thephysical antenna is illustrated by a main node 11 interconnected with aremote radio unit 12 by means of a digital interface 13. The remoteradio unit 12 is in turn connected to or comprises the physical antenna14.

The digital interface 13 may be realized in different ways for differentstandards and different products depending on, e.g., bandwidth of thecommunication system. Examples of such digital interface comprise CommonPublic Radio Interface (CPRI) and Open Base Station Standard Initiative(OBSAI). Proprietary digital interfaces available on the market may alsobe used.

The scarce spectrum availability makes the implementation of spectralefficient telecom systems highly desirable. Spectral efficiency isachieved in many different ways but recently two main directions thatare if interest here can be noted. One is towards adding more antennasat each node (more antennas per radio unit or more radio units per site)making it possible to utilize MIMO or beam-forming capabilities. Theother trend is to use more centralized processing in terms ofdata-link-layer (Layer 2) scheduling for DL and UL but also in terms ofjoint physical-layer processing of data from several sites. Both theaddition of antennas and the requirement of centralized processing leadto higher bandwidth requirements on the digital interface between themain unit and the radio unit(s). The implementation of high-bandwidthdigital interfaces is difficult technically as well as costly, and it istherefore desirable to keep the bandwidth requirements on the digitalinterface to a minimum.

SUMMARY

An object of the invention is to address and at least mitigate theabove-mentioned problem. In particular, it is an object of the inventionto enable reduction of the required capacity of the digital interfacebetween a main node and a remote radio node.

The object is according to a first aspect achieved by an integratedantenna node for use in wireless communication in a communicationsystem. The wireless communication involves uplink and downlinkphysical-layer processing, and the integrated antenna node is adapted toperform, for at least one set of corresponding uplink and downlinkphysical-layer processing functions, only the uplink physical-layerprocessing functions or the corresponding downlink physical-layerprocessing functions.

By integrating e.g. some of the downlink physical-layer processingfunctions, and not all of the corresponding uplink physical-layerprocessing functions, an asymmetry is constructed that leads to asubstantially lower bandwidth requirement on the digital interface forthe downlink while still allowing for centralized processing in a mainnode of the uplink. The reduced capacity need of the digital interfacegives large cost reductions, and the maintained centralized processingof the uplink gives high spectral efficiency.

The object is according to a second aspect achieved by a methodperformed in an integrated antenna node for use in wirelesscommunication in a communication system. The wireless communicationinvolves uplink and downlink physical-layer processing. The methodcomprises performing, for at least one set of corresponding uplink anddownlink physical-layer processing functions, only the uplinkphysical-layer processing functions or the corresponding downlinkphysical-layer processing functions.

The object is according to a third aspect achieved by a computer programfor an integrated antenna node for use in wireless communication in acommunication system. The wireless communication involves uplink anddownlink physical-layer processing. The computer program comprisescomputer program code which, when run on the integrated antenna node,causes the integrated antenna node to perform, for at least one set ofcorresponding uplink and downlink physical-layer processing functions,only the uplink physical-layer processing functions or the correspondingdownlink physical-layer processing functions.

The object is according to a fourth aspect achieved by a computerprogram product comprising a computer program as above and a computerreadable means on which the computer program is stored.

The object is according to a fifth aspect achieved by a main node foruse in a wireless communication system. The wireless communicationinvolves uplink and downlink physical-layer processing. The main node isadapted to perform, for at least one set of corresponding uplink anddownlink physical-layer processing functions, only the uplinkphysical-layer processing functions or the corresponding downlinkphysical-layer processing functions.

The object is according to a sixth aspect achieved by a method performedin a main node for use in a wireless communication system. The wirelesscommunication involves uplink and downlink physical-layer processing.The method comprises performing, for at least one set of correspondinguplink and downlink data link-layer processing functions, only theuplink data link-layer processing functions or the correspondingdownlink data link-layer processing functions.

The object is according to a seventh aspect achieved by a computerprogram for a main node (for use in a wireless communication system. Thewireless communication involves uplink and downlink physical-layerprocessing. The computer program comprises computer program code which,when run on the main node, causes the main node to perform, for at leastone set of corresponding uplink and downlink data link-layer processingfunctions, only the uplink data link-layer processing functions or thecorresponding downlink data link-layer processing functions.

The object is according to a eighth aspect achieved by a computerprogram product comprising a computer program as above and a computerreadable means on which the computer program is stored.

The object is according to a ninth aspect achieved by a radio basestation for wireless communication in a communication system. Thewireless communication involves uplink and downlink physical-layerprocessing. The radio base station comprises an integrated antenna nodeand a main node arranged to exchange data by means of an asymmetricdigital interface. The integrated antenna node and the main node are,respectively, arranged to perform, for at least one set of correspondinguplink and downlink data link-layer processing functions, only theuplink data link-layer processing functions or the correspondingdownlink data link-layer processing functions.

The object is according to a tenth aspect achieved by a method performedin a radio base station for wireless communication in a communicationsystem. The wireless communication involves uplink and downlinkphysical-layer processing. The radio base station comprises anintegrated antenna node and a main node exchanging data by means of anasymmetric digital interface. The method comprises performing in theintegrated antenna node and the main node, respectively, for at leastone set of corresponding uplink and downlink data link-layer processingfunctions, only the uplink data link-layer processing functions or thecorresponding downlink data link-layer processing functions.

Further features and advantages of the invention will become clear uponreading the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates two known radio base station architectures.

FIG. 2 illustrates schematically an environment in which embodiments ofthe invention may be implemented.

FIG. 3 illustrates a generalized flowchart of physical-layer of acommunication system.

FIG. 4 illustrates a general functional allocation of physical-layerprocessing in accordance with aspects of the invention.

FIG. 5 illustrates a first example of the asymmetric functional split.

FIG. 6 illustrates a second example of the asymmetric functional split.

FIG. 7 illustrates a third example of the asymmetric functional split.

FIG. 8 illustrates a fourth example of the asymmetric functional split.

FIG. 9 illustrates a flow chart over methods performed in the differentnodes.

FIG. 10 illustrates an exemplifying integrated antenna node comprisingmeans for implementing embodiments of various aspects of the invention.

FIG. 11 illustrates an exemplifying main node comprising means forimplementing embodiments of various aspects of the invention.

FIG. 12 illustrates an exemplifying radio base station comprising meansfor implementing embodiments of various aspects of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following description, for purposes of explanation and notlimitation, specific details are set forth such as particulararchitectures, interfaces, techniques, etc. in order to provide athorough understanding. In other instances, detailed descriptions ofwell-known devices, circuits, and methods are omitted so as not toobscure the description with unnecessary detail. Same reference numeralsrefer to same or similar elements throughout the description.

FIG. 2 illustrates schematically an environment in which embodiments ofthe invention may be implemented. A communication system 20 comprisesone or more radio base stations 28. The radio base station 28 isarranged to communicate wirelessly with one or more user equipment 25using radio frequency transmitter(s) and receiver(s), for exampleutilizing multiple-input multiple-output (MIMO) antenna technology. Aradio base station is denoted differently in different communicationsystems, e.g. denoted evolved Node B or eNB in communication systemsconforming to Long Term Evolution (LTE) standards. It is noted that theinvention is not restricted to any particular standard, and thecommunication system 20 may implement any standard such as e.g. LTE,Wideband Code-Division Multiple Access (WCDMA), Code-Division MultipleAccess 2000 (CDMA2000), Global System for Mobile Communications (GSM) orWorldwide Interoperability for Microwave Access (WiMAX).

The communication in the communication system 20 is wirelesscommunication, which involves uplink and downlink signal processing invarious layer levels. In particular, the wireless communicationcomprises uplink and downlink physical-layer processing (also denotedlayer one processing) and also higher level layer processing, such asdata link-layer processing (also denoted layer two processing) andcontrol-layer processing.

The radio base station 28 comprises a main node 21, in the followingalso denoted main unit, and an integrated antenna node 22, in thefollowing also denoted integrated antenna unit. The main node 21 and theintegrated antenna node 22 are arranged to exchange data by means of anasymmetric digital interface 23.

The integrated antenna node 22 comprises or is connected to a physicalantenna 24 transmitting and receiving signaling to/from the userequipment 25. That is, the physical antenna may be integrated with theintegrated antenna node or the physical antenna 24 may be a separatepart connected to the integrated antenna node 22.

The main node 21 may be connected to further integrated antenna units 32(here illustrated as integrated with the physical antenna 34),exchanging data over an asymmetric digital interface 33.

Conventionally, the allocation of functionality between the integratedantenna unit 22 and the main node 21 is symmetrical between the downlink(DL) and the uplink (UL), making the required bandwidth the same or atleast similar in both directions. This is illustrated in FIG. 3.

In particular, FIG. 3 illustrates a simplified generalized flowchart ofa physical layer of the communication system 20.

The top half shows some basic processing blocks for the downlink and thebottom half shows some corresponding processing blocks for the uplink.The physical layer thus comprises downlink and uplink physical-layerprocessing, exemplified by different physical-layer processingfunctions: encoding 80/decoding, modulation 81/demodulation 86,beamforming, precoding 82/equalization 85, signal shaping 83/signalextraction 84.

The width of the arrows in-between the blocks signifies the relativebandwidth requirements for data between the blocks. It can be seen thatthe bandwidth requirement increases further and further down thedownlink processing chain, while it decreases further and further alongthe uplink processing chain.

The bandwidth difference arises from, inter alia: redundancy for errorprotection, multiplexing of data with physical-layer generated controlsignaling as well as physical signals used for synchronization andmeasurements, change of numerical representation from bits to (complex-)valued integers represented by several bits (i.e., modulation),multi-antenna processing where symbols are mapped to one or severalantennas, etc. FIG. 3 illustrates the split between the main node andthe integrated antenna node as it is traditionally done. As explainedearlier, this split results in a high bandwidth requirement between themain node and the integrated antenna node for both downlink and uplinkand a low level of integration of physical-layer digital-processingunits into the integrated antenna node.

It is noted that only the physical-layer processing for the main nodeand the integrated antenna node is illustrated in FIG. 3. Although notillustrated, the integrated antenna node comprises radio implementationblocks such as channelization and RF-processing (refer also to FIG. 8).Likewise, although not illustrated, the main node comprises data-linklayer blocks such as, e.g., radio-link control processing (refer also toFIG. 8).

In contrast to the above, the present invention provides, in variousaspects, an asymmetric functionality split with respect to the downlinkand the uplink, between the main node 21 and the integrated antenna node22. This is realized by integrating many (or some) of the downlinkprocessing functions into the integrated antenna node 22 but keepingmost (or all) of the uplink processing functions in the main unit 21.This asymmetry leads to a substantially lower bandwidth requirement onthe digital interface 23 for the downlink while still allowing forcentralized processing of the uplink, where it is beneficial in order toaccomplish high spectral efficiency.

FIG. 4 illustrates schematically this asymmetrical functionality split.In the illustrated example, the main node 21 comprises more uplinkphysical-layer processing functions than the integrated antenna node 22,and fewer downlink physical-layer processing function than theintegrated antenna node 22. These differences are illustrated by thesize of the respective boxes. The asymmetrical functionality split thengives different bandwidth requirements in uplink and downlink,respectively, which is illustrated by the size of the arrows between thenodes 21, 22.

In the following some aspects are given on how to split thefunctionality between the integrated antenna node 22 and the main node21.

To couple the same main node 21 to several integrated antenna nodes 22enables a more advanced processing in the uplink using data from severalantennas, which meets the requirements for increased spectralefficiency. When implementing the present invention, it is noted thatthe processing blocks in the uplink are expected to be flexible and thecoupling between the implemented standard such as, e.g., LTE, WCDMA, orWiMax and the choice of algorithms and/or implementation strategies israther flexible.

In the downlink, the processing blocks are more tightly coupled to theimplemented standard and therefore there is a reduced need forflexibility in these blocks. Moreover, the downlink processing blocksmay be realized in accelerator blocks or by highly dedicated functionsin general-purpose processors. This facilitates the integration of theseblocks into the integrated antenna node 22.

That is, the integrated antenna node(s) 22 may be configured once withthe desired uplink/downlink processing blocks, while the flexibility inthe main node 21 provides the advantage of being able to updateconfigurations at only one place per several integrated antenna nodes22.

Thus, localization of the uplink processing blocks in the main node 21instead of integrating them into each of the integrated antenna nodes 22is advantageous. It is also noted that, in various embodiments, thespectral efficiency effecting the downlink processing is related tohigher-layer functionality, such as scheduling or radio-resourcemanagement (RRM), which has limited impact on the physical-layerdownlink blocks. This in turn again favors the integration of downlinkphysical-layer processing in the integrated antenna node 22.

The integration of several of the downlink processing blocks into theintegrated antenna node 22, but keeping many (or all) of the uplinkprocessing blocks in the main node 21 reduces the bandwidth requirementin the downlink interface between the main unit 21 and the integratedantenna nodes 22, while keeping the flexibility needed for thepotentially centralized uplink processing. Aspects of the invention canbe realized in several ways, and a few examples are given in thefollowing.

In the following FIGS. 5, 6 and 7, only the physical-layer processingfor the main node 21 and the integrated antenna node 22 is illustrated.Although not illustrated, the integrated antenna node 22 comprises radioimplementation blocks such as channelization and RF-processing (referalso to FIG. 8). Likewise, although not illustrated, the main nodecomprises data-link layer blocks such as, e.g., radio-link controlprocessing (refer also to FIG. 8).

FIG. 5 illustrates a first example of the asymmetric functional splitbetween the main unit 21 and integrated antenna node 22, i.e., thepartition of physical-layer processing blocks between the nodes 21, 22.The downlink processing blocks are exemplified by modulation 101,beamforming/precoding 102, and signal shaping 103, which blocks areintegrated into the integrated antenna node 22. This results in a largereduction in bandwidth requirement for the downlink. The uplink is leftwith the traditional split between the main unit 21 and the integratedantenna node 22. That is, the uplink processing blocks, exemplified ascomprising signal extraction 200, equalization 201, demodulation 202,decoding 203, are integrated into the main unit 21 along with anencoding processing block 100 for the downlink.

As mentioned earlier, the wireless communication involves uplink anddownlink physical-layer processing, and all processing blocksexemplified above are related to such physical-layer processing (layerone).

It is, however, noted that the functional split can be performed athigher levels also, e.g. data link-layer processing (layer two).

In this regard it is also noted that the uplink and downlinkphysical-layer processing functions, may be seen as comprising sets ofcorresponding uplink and downlink physical-layer processing functions.For example, one such set of corresponding uplink and downlinkphysical-layer processing functions could comprise demodulation 202 andmodulation 101, and another such set could comprise equalization 201 andbeamforming/precoding 102. Sometimes the corresponding uplink anddownlink physical-layer processing functions, or sub-functions thereof,are reverse or even inverse functions of each other, e.g. Fast FourierTransform (FFT)/Inverse Fast Fourier Transform (IFFT).

For different standards, the different sets of corresponding uplink anddownlink physical-layer processing functions comprise differentsub-functions. For example, in LTE, which uses the radio-accesstechnologies Orthogonal Frequency-Division Multiplexing (OFDM) in thedownlink and Single-Carrier-Frequency Domain Multiple Access (SC-FDMA)in the uplink, the set of corresponding processing functions comprisingsignal shaping/signal extraction comprises IFFT/FFT and cyclic prefixinsertion/removal. That is, the downlink physical-layer processingfunction “signal shaping” comprises the sub-functions IFFT and cyclicprefix insertion and the corresponding uplink physical-layer processingfunction, i.e. the signal extraction, comprises FFT and cyclic prefixremoval. As another example, in WCDMA/CDMA/Time-Division SynchronousCode-Division Multiple Access (TD-SCDMA), which all use the radio-accesstechnology CDMA, signal shaping/signal extraction comprisesSpreading/Despreading.

It is also noted that in other instances, the number of sub-functionsperformed in an uplink physical-layer processing function may differfrom the number of corresponding downlink physical-layer processingfunctions.

Equalization may comprise channel estimation and signal equalization,performed by different methods such as e.g. RAKE, G-RAKE, maximal-ratiocombining (MRC), Interference-Rejection Combining (IRC), MinimumMean-Squared Error (MMSE), joint detection (JD), Successive InterferenceCancellation (SIC), Parallel Interference Cancellation (PIC), or MaximumLikelihood (ML).

The expression “set of corresponding uplink and downlink physical-layerprocessing functions” should thus be interpreted as including all suchdifferent variations.

FIG. 6 illustrates a second example of the asymmetric functional split,i.e., the partition of physical-layer processing blocks between the mainnode 21 and the integrated antenna node 22. In this embodiment, thedownlink encoding block 100 is also integrated into the integratedantenna node 22, further reducing the required bandwidth. Here theuplink signal extraction block 200 is also integrated into theintegrated antenna node 22, reducing the bandwidth requirement on theuplink interface somewhat as well.

FIG. 7 illustrates a third example of the asymmetric functional split,i.e., the partition of physical-layer processing blocks between the mainnode 21 and the integrated antenna node 22. In this embodiment, allmulti-antenna related processing, such as beamforming/precoding 102, isperformed in the integrated antenna node 22, while bit and symbolprocessing 100, 101, 201, 202, 203 are still done in the main node 21.

From the above it is realized that the functional split can beimplemented and varied in different ways. Some aspects of the choice ofhow to do the functional split have already been given. Further, thefunctional split is dependent on, e.g., the communication system forwhich this is implemented, but also on implementation aspects such asavailable processing blocks, cross-signaling and synchronization betweendownlink and uplink processing blocks, available digital interfaces,etc.

The asymmetric functionality split, with respect to uplink and downlink,between the main node 21 and the integrated antenna node 22 is alsobeneficial for system flexibility. Each integrated antenna node 22 canbe adapted to support an increasing number of antennas withoutnecessarily affecting the main node 21. In much the same way, a mainnode 21 can be adapted to support several integrated antenna nodes 22without affecting the internal functionality of the integrated antennanode 22 if carefully choosing the functionality split between them.

As a particular example an LTE system of Release 10 (or later) is used.On downlink it supports up to two transport blocks (data streams) and upto 8 transmit (Tx) antenna ports. With a main node 21/integrated antennanode 22 split according to FIG. 7, the processing of the transportblocks in the main node 21 is independent of the number of antenna portssupported in the integrated antenna node 22. The antenna port-relatedprocessing in the integrated antenna node 22, e.g., thebeamforming/precoding and the signal shaping, must be adapted to theactual number of antenna ports in use.

For the above example, in the event of Coordinated Multi-Point (DL CoMP)transmission, the main node 21/integrated antenna node 22 split can belocated after the modulation block 101, and the modulated data streamsare distributed to several geographically separated integrated antennanodes 22 with further processing adapted for CoMP. Hence, one main unit21 supports several integrated antenna nodes 22.

On uplink, joint processing of data from several antenna sites can beused. Hence, multiple integrated antenna nodes 22 feed data to a singlemain unit 21. In this case the main node 21/integrated antenna node 22split depends on the receiver/decoding algorithms used. For ML decodingor SIC processing, the unprocessed antenna samples are needed in themain node 21, which limits the integrated antenna node 22 processing tosignal extraction. When using simpler signal-combining schemes in themain node 21, more receiver processing can be performed in eachintegrated antenna node 22, thus reducing the bandwidth requirementbetween the integrated antenna nodes 22 and the main node 21 at theexpense of overall receiver performance.

One example of typical interface savings is presented next. Note thatthis should serve only as an example and the numbers used may notexactly match those in a real system. Nevertheless, this is indicativeof the potential gain that can be achieved by using the architecturedisclosed herein.

Assume an LTE system with four transmit antennas and 20 MHz channelband-width. The downlink peak rate of such a system would be in theorder of 300 Mbps (2×149 776 bits can be transmitted each subframe of 1ms). If the split depicted in FIG. 6 is used, the capacity of thedigital interface would be of this order. Some overhead can be expected,but the order of magnitude would at least be correct.

For comparison, with a traditional split between main unit 21 andintegrated antenna node 22 an order of magnitude higher capacity wouldbe needed. In this case the data bits would be encoded, modulated,precoded, and then OFDM processed. A typical sampling frequency for sucha system would be approximately 30 Msample/s, and if each sample isrepresented with 30 bits, a total of 30×30×4=3600 Mbps need to betransmitted between the main node 21 and integrated antenna node 22 fordownlink data of one cell only.

FIG. 8 illustrates a fourth example of the asymmetric functional split.Above, the functional split has been exemplified for the physical layeronly (layer one), but as mentioned, the functional split can beperformed at higher levels also, e.g. data link-layer processing (layertwo), which is illustrated in FIG. 8. In particular, the asymmetricfunctional split, with respect to uplink and downlink, between the mainnode 21 and the integrated antenna node 22 is shown. In the illustratedexample, data link-layer (layer 2) processing functions are integratedinto the integrated antenna node 22, in particular the data link-layerprocessing functions medium-access control processing for downlink.

FIG. 9 illustrates a flow chart of methods performed in the differentnodes 21, 22, 28 of the communication system 20.

In an aspect, a method 30 performed in the integrated antenna node 22for use in wireless communication in the communication system 20 isprovided. The wireless communication involves, as described, uplink anddownlink physical-layer processing. The method 30 comprises performing31, for at least one set of corresponding uplink and downlinkphysical-layer processing functions, only the uplink physical-layerprocessing functions or the corresponding downlink physical-layerprocessing functions.

In another aspect, and still with reference to FIG. 9, a method 40performed in the main node 21 for use in a wireless communication system20 is provided. The wireless communication involves uplink and downlinkphysical-layer processing. The method 40 comprises performing 41, for atleast one set of corresponding uplink and downlink data link-layerprocessing functions, only the uplink data link-layer processingfunctions or the corresponding downlink data link-layer processingfunctions.

In still another aspect, again with reference to FIG. 9, a method 50performed in a radio base station 28 for wireless communication in acommunication system 20 is provided. The wireless communication involvesuplink and downlink physical-layer processing, and the radio basestation 28 comprises an integrated antenna node 22 and a main node 21exchanging data by means of an asymmetric digital interface 23. Themethod 50 comprises performing 51 in the integrated antenna node 22 andthe main node 21, respectively, for at least one set of correspondinguplink and downlink data link-layer processing functions, only theuplink data link-layer processing functions or the correspondingdownlink data link-layer processing functions.

FIG. 10 illustrates an exemplifying integrated antenna node comprisingmeans for implementing embodiments of various aspects of the invention.The integrated antenna node 22 is suitable for use in wirelesscommunication in the communication system 20 as described. The wirelesscommunication involves uplink and downlink physical-layer processing,and the integrated antenna node 22 is adapted to perform, for at leastone set of corresponding uplink and downlink physical-layer processingfunctions, only the uplink physical-layer processing functions or thecorresponding downlink physical-layer processing functions.

In an embodiment, the integrated antenna node 22 is adapted to performall downlink physical-layer processing functions performed in thecommunication system 20.

In an embodiment, the uplink physical-layer processing functions 200,201, 202, 203 comprise one or more of: signal extraction 200,equalization 201, demodulation 202, decoding 203, medium-access controlprocessing, and radio link control processing.

In an embodiment, the downlink physical-layer processing functions 100,101, 102, 103 comprise one or more of: encoding 100, modulation 101,beam-forming and pre-coding 102, signal shaping 103, medium-accesscontrol processing, and radio-link control processing.

In an embodiment, the integrated antenna node 22 comprises anasymmetrical digital interface 23 for exchanging data with the main node21 also adapted to perform uplink and downlink physical-layer processingfunctions in the wireless communication system 20.

In an embodiment, the wireless communication further involves uplink anddownlink data link-layer processing, the integrated antenna node 22 isthen adapted to perform, for at least one set of corresponding uplinkand downlink data link-layer processing functions, only the uplink datalink-layer processing functions or the corresponding downlink datalink-layer processing functions.

In particular, the integrated antenna node 22 comprises a number ofdownlink processing function modules 47, the number being at least onesuch module. The number of and which downlink processing functionmodules 47 to include have been exemplified thoroughly earlier.

The integrated antenna node 22 may further comprise a number of uplinkprocessing function modules 48. In one embodiment, the integratedantenna node 22 comprises none of such uplink processing function module48, i.e., all uplink processing is performed in the main node 21. Thenumber of and which uplink processing function modules 47 to includehave been exemplified thoroughly earlier.

The integrated antenna node 22 further comprises a processing unit 43.It is noted that although the processing unit 43 is illustrated as asingle unit, it may not only be a single processing unit, but couldcomprise two or more processing units. The processing unit 43 may forexample comprise general purpose microprocessors, reducedinstruction-set processors and/or related chips sets and/or specialpurpose microprocessors, such as ASICs (application-specific integratedcircuits), or Field-Programmable Gate Arrays (FPGA). The processing unit43 may also comprise board memory for caching purposes.

The processing unit 42 is operatively connected to the downlinkprocessing function modules 47 and the uplink processing functionmodules 48, and configured to enable the functions of the integratedantenna node 22.

The integrated antenna node 22 may also comprise receiver circuitry 42and transmitter circuitry 43 for signal reception and transmission bymeans of the physical antenna(s) 24.

It is noted that the uplink and downlink processing function modules 48,47 (e.g. modules for physical-layer processing functions and the datalink-layer processing functions) may be implemented in hardware,software, firmware or any combination thereof.

The physical-layer processing functions and the data link-layerprocessing functions may be implemented as program modules of a computerprogram 44 comprising code means which when run by the processing unit43 in the integrated antenna node 22 causes the integrated antenna node22 to perform the above-described functions and actions. The computerprogram 44 may be carried by a computer program product 45 in theintegrated antenna node 22 connected to the processing unit 43. Thecomputer program product 45 comprises a computer readable medium onwhich the computer program 44 is stored. For example, the computerprogram product 45 may be a flash memory, a RAM (Random-access memory),ROM (Read-Only memory) or an EEPROM (Electrically Erasable ProgrammableROM), and the computer program modules described above could inalternative embodiments be distributed on different computer programproducts in the form of memories within the integrated antenna node 22.The computer program product 45 may for example be an optical disc, suchas a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Raydisc.

Still with reference to FIG. 10, the invention also encompasses thecomputer program 44 for the integrated antenna node 22 as described forwireless communication as also described. The computer program 44comprises computer program code which, when run on the integratedantenna node 22, causes the integrated antenna node 22 to perform, forat least one set of corresponding uplink and downlink physical-layerprocessing functions, only the uplink physical-layer processingfunctions or the corresponding downlink physical-layer processingfunctions.

Still with reference to FIG. 10, the invention also encompasses acomputer program product 45 comprising a computer program 44 asdescribed above, and a computer readable means on which the computerprogram 44 is stored.

The integrated antenna node 22 further comprises an interface unit 46implementing and enabling asymmetric communication with the main node 21over the asymmetric digital interface 23 used for exchanging databetween the nodes 21, 22. The interface unit 46 may for example comprisean input/output system and an associated protocol.

FIG. 11 illustrates an exemplifying main node comprising means forimplementing embodiments of various aspects of the invention. The mainnode 21 for use in a wireless communication system 20, wherein thewireless communication involves uplink and downlink physical-layerprocessing. The main node 21 is adapted to perform, for at least one setof corresponding uplink and downlink physical-layer processingfunctions, only the uplink physical-layer processing functions or thecorresponding downlink physical-layer processing functions.

In an embodiment, the main node 21 is arranged to perform all uplinkphysical-layer processing functions performed in the communicationsystem 20.

In an embodiment, the uplink physical-layer processing functions 200,201, 202, 203 comprise one or more of: signal extraction 200,equalization 201, demodulation 202, decoding 203, medium-access controlprocessing, and radio link control processing.

In an embodiment, the downlink physical-layer processing functions 100,101, 102, 103 comprise one or more of: encoding 100, modulation 101,beam-forming and pre-coding 102, signal shaping 103, medium-accesscontrol processing, and radio link control processing.

In an embodiment, the main node 21 further comprises an asymmetricdigital interface 23 for exchanging data with an integrated antenna node22 which is also adapted to perform uplink and downlink physical-layerprocessing functions in the wireless communication system 20.

In an embodiment, the wireless communication further involves uplink anddownlink data link-layer processing, and the main node 21 is thenfurther adapted to perform, for at least one set of corresponding uplinkand downlink data link-layer processing functions, only the uplink datalink-layer processing functions or the corresponding downlink datalink-layer processing functions.

In particular, the main node 21 comprises a number of downlinkprocessing function modules 55. In one embodiment, the main node 21comprises none of such downlink processing function module 55, i.e. alldownlink processing is performed in the integrated antenna node 22. Thenumber of and which downlink processing function modules 47 to includehave been exemplified thoroughly earlier.

The main node 21 comprises a number of uplink processing functionmodules 56, the number being at least one such module. The number of andwhich uplink processing function modules 47 to include have beenexemplified thoroughly earlier.

The main node 21 further comprises a processing unit 52. It is notedthat although the processing unit 52 is illustrated as a single unit, itmay not only be a single processing unit, but could comprise two or moreprocessing units. The processing unit 52 may for example comprisegeneral purpose microprocessors, reduced instruction set processorsand/or related chips sets and/or special purpose microprocessors, suchas ASICs (application-specific integrated circuits), orField-Programmable Gate Array (FPGA). The processing unit 52 may alsocomprise board memory for caching purposes.

The processing unit 52 is operatively connected to the downlinkprocessing function modules 55 and the uplink processing functionmodules 56, and configured to enable the functions of the main node 21.

It is noted that the uplink and downlink processing function modules 55,56 (e.g. modules for physical-layer processing functions and the datalink-layer processing functions) may be implemented in hardware,software, firmware or any combination thereof.

The physical-layer processing functions and the data link-layerprocessing functions may be implemented as program modules of a computerprogram 53 comprising code means which when run by the processing unit52 in the main node 21 causes the main node 21 to perform theabove-described functions and actions. The computer program 53 may becarried by a computer program product 54 in the main node 21 connectedto the processing unit 52. The computer program product 54 comprises acomputer readable medium on which the computer program 53 is stored. Forexample, the computer program product 54 may be a flash memory, a RAM(Random-access memory), ROM (Read-Only memory) or an EEPROM(Electrically Erasable Programmable ROM), and the computer programmodules described above could in alternative embodiments be distributedon different computer program products in the form of memories withinthe main node 21. The computer program product 54 may for example be anoptical disc, such as a CD (compact disc) or a DVD (digital versatiledisc) or a Blu-Ray disc.

Still with reference to FIG. 11, the invention also encompasses computerprogram 53 for the main node 21 as described for wireless communicationas also described. The computer program 53 comprises computer programcode which, when run on the main node 21, causes the main node 21 toperform, for at least one set of corresponding uplink and downlinkphysical-layer processing functions, only the uplink physical-layerprocessing functions or the corresponding downlink physical-layerprocessing functions.

Still with reference to FIG. 11, the invention also encompasses acomputer program product 54 comprising a computer program 53 asdescribed above, and a computer readable means on which the computerprogram 53 is stored.

The main node 21 further comprises an interface unit 51 implementing andenabling asymmetric communication with the integrated antenna node 22over the asymmetric digital interface 23 used for exchanging databetween the nodes 21, 22. The interface unit 51 may for example comprisean input/output system and an associated protocol.

FIG. 12 illustrates an exemplifying radio base station comprising meansfor implementing embodiments of various aspects of the invention. Theradio base station 28 is used for wireless communication in thecommunication system 20 as described, wherein the wireless communicationinvolves uplink and downlink physical-layer processing. The radio basestation 28 comprise the integrated antenna node 22 and the main node 21which are arranged to exchange data by means of the asymmetric digitalinterface 23. The integrated antenna node 22 and the main node 21,respectively, are arranged to perform, for at least one set ofcorresponding uplink and downlink data link-layer processing functions,only the uplink data link-layer processing functions or thecorresponding downlink data link-layer processing functions.

In particular, the radio base station comprises the integrated antennanode 22 as described with reference to FIG. 10 and the main node 21 asdescribed with reference to FIG. 11. The radio base station 28 alsocomprises the asymmetric digital interface 23, by means of which themain node 21 and the integrated antenna node 22 exchanges data. Theasymmetric digital interface 23 may comprise a synchronous asymmetricinterface or an asynchronous asymmetric interface.

1. An integrated antenna node for use in wireless communication in acommunication system, the wireless communication involving uplink anddownlink physical-layer processing, the integrated antenna node beingadapted to: perform, for at least one set of corresponding uplink anddownlink physical-layer processing functions, only the uplinkphysical-layer processing functions or the corresponding downlinkphysical-layer processing functions.
 2. The integrated antenna node asclaimed in claim 1, adapted to perform all downlink physical-layerprocessing functions performed in the communication system.
 3. Theintegrated antenna node as claimed in claim 1, wherein the uplinkphysical-layer processing functions comprise one or more of: signalextraction, equalization, demodulation, decoding, medium-access controlprocessing, and radio link control processing.
 4. The integrated antennanode as claimed in claim 1, wherein the downlink physical-layerprocessing functions comprise one or more of: encoding, modulation,beam-forming and pre-coding, signal shaping, medium-access controlprocessing, and radio link control processing.
 5. The integrated antennanode as claimed in claim 1, further comprising an asymmetrical digitalinterface for exchanging data with a main node also adapted to performuplink and downlink physical-layer processing functions in the wirelesscommunication system.
 6. The integrated antenna node as claimed in claim1, wherein the wireless communication further involves uplink anddownlink data link-layer processing, the integrated antenna node beingadapted to: perform, for at least one set of corresponding uplink anddownlink data link-layer processing functions, only the uplink datalink-layer processing functions or the corresponding downlink datalink-layer processing functions.
 7. A method performed in an integratedantenna node for use in wireless communication in a communicationsystem, the wireless communication involving uplink and downlinkphysical-layer processing, the method comprising: performing, for atleast one set of corresponding uplink and downlink physical-layerprocessing functions, only the uplink physical-layer processingfunctions or the corresponding downlink physical-layer processingfunctions.
 8. A computer program for an integrated antenna node for usein wireless communication in a communication system, the wirelesscommunication involving uplink and downlink physical-layer processing,the computer program comprising computer program code which, when run onthe integrated antenna node, causes the integrated antenna node to:perform, for at least one set of corresponding uplink and downlinkphysical-layer processing functions, only the uplink physical-layerprocessing functions or the corresponding downlink physical-layerprocessing functions.
 9. A computer program product comprising acomputer program as claimed in claim 8, and a computer readable means onwhich the computer program is stored.
 10. A main node for use in awireless communication system, the wireless communication involvinguplink and downlink physical-layer processing, the main node beingadapted to: perform, for at least one set of corresponding uplink anddownlink physical-layer processing functions, only the uplinkphysical-layer processing functions or the corresponding downlinkphysical-layer processing functions.
 11. The main node as claimed inclaim 10, arranged to perform all uplink physical-layer processingfunctions performed in the communication system.
 12. The main node asclaimed in claim 10, wherein the uplink physical-layer processingfunctions comprise one or more of: signal extraction, equalization,demodulation, decoding, medium-access control processing, and radio linkcontrol processing.
 13. The main node as claimed in claim 10, whereinthe downlink physical-layer processing functions comprise one or moreof: encoding, modulation, beam-forming and pre-coding, signal shapingmedium-access control processing, and radio link control processing. 14.The main node as claimed in claim 10, further comprising an asymmetricdigital interface for exchanging data with an integrated antenna nodealso adapted to perform uplink and downlink physical-layer processingfunctions in the wireless communication system.
 15. The main node asclaimed in claim 10, wherein the wireless communication further involvesuplink and downlink data link-layer processing, the main node beingadapted to: perform, for at least one set of corresponding uplink anddownlink data link-layer processing functions, only the uplink datalink-layer processing functions or the corresponding downlink datalink-layer processing functions.
 16. A method performed in a main nodefor use in a wireless communication system, the wireless communicationinvolving uplink and downlink physical-layer processing, the methodcomprising: performing, for at least one set of corresponding uplink anddownlink data link-layer processing functions, only the uplink datalink-layer processing functions or the corresponding downlink datalink-layer processing functions.
 17. A computer program for a main nodefor use in a wireless communication system, the wireless communicationinvolving uplink and downlink physical-layer processing, the computerprogram comprising computer program code which, when run on the mainnode, causes the main node to: perform, for at least one set ofcorresponding uplink and downlink data link-layer processing functions,only the uplink data link-layer processing functions or thecorresponding downlink data link-layer processing functions.
 18. Acomputer program product comprising a computer program as claimed inclaim 17, and a computer readable means on which the computer program isstored.
 19. A radio base station for wireless communication in acommunication system, the wireless communication involving uplink anddownlink physical-layer processing, the radio base station comprising anintegrated antenna node and a main node arranged to exchange data bymeans of an asymmetric digital interface, and wherein the integratedantenna node and the main node are, respectively, arranged to perform,for at least one set of corresponding uplink and downlink datalink-layer processing functions, only the uplink data link-layerprocessing functions or the corresponding downlink data link-layerprocessing functions.
 20. A method performed in a radio base station forwireless communication in a communication system, the wirelesscommunication involving uplink and downlink physical-layer processing,the radio base station comprising an integrated antenna node and a mainnode exchanging data by means of an asymmetric digital interface, themethod comprising: performing in the integrated antenna node and themain node, respectively, for at least one set of corresponding uplinkand downlink data link-layer processing functions, only the uplink datalink-layer processing functions or the corresponding downlink datalink-layer processing functions.